Stabilizing vertebrae with expandable spacers

ABSTRACT

A spinal distracter and stabilizer has resilient, conformable bone contacting sections which are separated by an expandable chamber that extends from one of the sections, and which forms a ratchet with the section, ensuring that once expanded by being filled with a substance, cannot contract absent intervention by a medical practitioner. The stabilizer may be filled with a material which solidifies, after which some or all of the device may biodegrade. The device may also be provided in separable portions to facilitate implantation. The conformable sections distribute the distraction and stabilizing force evenly over the bone surface, reducing the incidence of disruption to the integrity of the bone.

FIELD OF THE INVENTION

The invention relates to systems and methods for stabilizing andrestoring intervertebral spacing, and in particular, to expandable orinflatable intervertebral implants.

BACKGROUND OF THE INVENTION

The vertebral or spinal column is a flexible assembly of vertebraestacked on top of each other extending from the skull to the pelvic bonewhich acts to support the axial skeleton and to protect the spinal cordand nerves. The vertebrae are anatomically organized into fourgeneralized body regions identified as cervical, thoracic, lumbar, andsacral; the cervical region including the top of the spine beginning inthe skull, the thoracic region spanning the torso, the lumbar regionspanning the second back, and the sacral region including the base ofthe spine ending with connection to the pelvic bone. With the exceptionof the first two cervical vertebrae, cushion-like intervertebral discsseparate adjacent vertebrae.

The stability of the vertebral column during compression and movement ismaintained by the intervertebral discs. Each disc includes a gel-likecenter surrounded by a fibrous ring. The gel-like center, or nucleuspulposus, provides strength and shock absorption, whereby the disc canabsorb and distribute external loads. The nucleus pulposus contains amixture of type II collagen dispersed in a proteoglycan matrix. Thefibrous ring, or annulus fibrosus, provides stability during motion, andcontains laminated rings of type-I collagen. Thus, the annulus fibrosisand the nucleus pulposus are interdependent, as the annulus fibrosiskeeps the nucleus pulposus in place, and the nucleus pulposus aligns theannulus fibrosus to accept/distribute external loads. The integrity ofthe composition and structure of the intervertebral disc is necessary tomaintain normal functioning of the intervertebral disc.

Many factors can adversely alter the composition and structure of theintevertebral disc, such as normal physiological aging, mechanicalinjury or trauma, or disease, resulting in impairment or loss of discfunction. For example, the content of proteoglycan in the nucleuspulposus declines with age, thus, it follows that the ability of thenucleus pulposus to absorb water concurrently declines. Therefore, innormal aging the disc progressively dehydrates, resulting in a decreasein disc height and possible de-lamination of the annulus fibrosus.Mechanical injury can tear the annulus fibrosis allowing the gel-likematerial of the nucleus pulposus to extrude into the spinal canal andcompress neural elements. Growth of a spinal tumor can impinge upon thevertebrae or disc, potentially compressing nerves. Regardless of thecause, many of these disc pathologies become severe enough to requiresurgical intervention.

In most cases, surgical intervention is a partial or complete removal ofthe damaged intervertebral disc material, and is termed a discectomy.While the discectomy may eliminate the problems associated with thedamaged disc, it creates a void in the intervertebral space that, ifleft empty, can destabilize and possibly collapse the vertebrae, withadverse consequences. A device may be placed within the intervertebralspace to increase stability, and to reduce the possibilities, forexample, of disc collapse or the displacement of intervertebral tissue.

The art described in this section is not intended to constitute anadmission that any patent, publication or other information referred toherein is “prior art” with respect to this invention, unlessspecifically designated as such.

SUMMARY OF THE INVENTION

In accordance with the disclosure, a joint distraction and stabilizationdevice comprises a first bone contacting section having a first surfaceconformable to a surface of a first bone on one side of the joint; asecond bone contacting section having a second surface conformable to asurface of a second bone on an opposite side of the joint; an expandableelement positionable between the first and second bone contactingsections, the expandable element having an inlet port through which afilling medium may be passed into the expandable element under a fillingpressure sufficient to expand and increase a dimension of the expandableelement along an axis extending between the first bone and the secondbone; at least one pawl extending from at least one of the first orsecond bone contacting sections; and at least one ratchet extending fromthe expandable element, the at least one ratchet passable past andengageable with the at least one pawl when the expandable element isexpanded by pressure, and not passable past the at least one pawl whenthe at least one ratchet and at least one pawl are engaged and thefilling pressure is reduced.

In various embodiments, at least one of the at least one pawl and atleast one of the at least one ratchet are resiliently deflectable to bepassable past the other; at least one of the at least one pawl and atleast one of the at least one ratchet are hinged to be passable past theother; the inlet port includes a valve operative to maintain a pressureof the filling medium within the expandable element; the fillable mediumincreases in solidity after being passed into the expandable element;and a substantial portion of the device biodegrades after the fillablemedium increases in solidity.

In yet further embodiments, the first and second bone contactingsections and the expandable element include mutually communicatingapertures whereby a channel is formed extending from the first bone tothe second bone; a material for promoting bone growth between the firstand second bones is placed inside the aperture; the first bonecontacting section includes a first side wall extending towards thesecond bone contacting section, and the second bone contacting sectionincludes a second side wall extending towards the first bone contactingsection, the first and second side walls telescoping in mutual relativeconformity.

In another embodiment, the spacer further includes an extensionextending from the inlet to a position away from bones of the joint; theextension is separable from the inlet; the spacer further includesprojections extending from at least one of the first and second bonecontacting sections to engage bone of the joint, thereby securing the atleast one of the first and second bone contacting sections from lateralmovement relative to an axis extending from the first bone to the secondbone; at least one of the first or second bone contacting sections isseparable from the expandable element.

In accordance with the disclosure, the bones may be of any joint in thebody, the device advantageously utilized for example where the bones arevertebral bodies.

In further embodiments, the expandable element is formed of a resilientmaterial; at least one of the first and second bone contacting sectionsresiliently conforms to a shape of the first or second bone,respectively; and the expandable element expands non-uniformly, therebydisposing the first and second bone contacting sections in substantiallynon-parallel conformity with respect to each other, when the first andsecond bone contacting sections are in contact with the first and secondbones, respectively.

An a further embodiment of the disclosure, a joint distraction andstabilization device for the spine, comprises a first bone contactingsection having a first resilient surface conforming to a surface of afirst vertebral endplate of a first vertebra; a second bone contactingsection having a second resilient surface conforming to a surface of asecond vertebral endplate of an adjacent, second vertebra; an expandableelement positioned between the first and second bone contactingsections, the expandable element having an inlet port through which afilling medium may be passed into the expandable element under a firstpressure to expand and increase a height of the expandable element alongan axis extending between the first bone and the second bone; at leastone pawl extending from at least one of the first or second bonecontacting sections; and at least one ratchet extending from theexpandable element, the at least one ratchet passable past andengageable with the at least one pawl when the expandable element isexpanded by pressure, and not passable past the at least one pawl whenthe at least one ratchet and at least one pawl are engaged and thefilling medium is under a second, lower pressure, whereby a height ofthe device is substantially maintained. In an embodiment, the at leastone pawl and the at least one ratchet are disengageable, whereby aheight of the device may be reduced.

In accordance with a yet further embodiment, a joint distraction andstabilization device for the spine, comprises first and second vertebralendplate contacting sections having first and second resilient surfaceshaving projections, respectively; and an expandable element positionedbetween the first and second vertebral endplate contacting sections andextendable from at least one of the first and second vertebralendplates, the expandable element having an inlet port through which afilling medium may be passed into the expandable element under a firstpressure to expand and increase a height of the expandable element alongan axis extending between the first bone and the second bone to therebydistract the joint, the first pressure further operative to cause thefirst resilient surface to resiliently conform to a surface of a firstvertebral endplate of a first vertebra, and to cause the secondresilient surface to resiliently conform to a surface of a secondvertebral endplate of an adjacent, second vertebra.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 depicts a spacer in accordance with the disclosure, in anon-expanded configuration;

FIG. 2 depicts the spacer of FIG. 1, expanded, illustrating convex boneengaging surfaces;

FIG. 3 depicts a cross-section through the spacer of FIG. 1, taken alongan axis extending between bones of a joint, the spacer positionedbetween bones of the joint, illustrating telescoping side walls and anexpandable interior reservoir or chamber, the spacer in a non-expandedconfiguration;

FIG. 4 depicts the spacer of FIG. 3, in an expanded configuration;

FIG. 5 depicts an alternative spacer in accordance with the disclosure,including resilient side walls, and a limiting tether, in an unexpandedconfiguration;

FIG. 6 depicts the spacer of FIG. 5, in an expanded configuration, alateral displacement limited by the tether;

FIG. 7 depicts a further embodiment of the disclosure, including anexpandable element having a through-hole for bone graft packing and asidewall including ratchets;

FIG. 8 depicts a detailed area of the embodiment of FIG. 7, illustratinga cross section through the spacer of FIG. 7, taken along a verticalaxis of the device, as illustrated, showing one embodiment ratchet andpawl configuration;

FIG. 9 depicts the detailed area of the embodiment of FIG. 7,illustrating an alternative embodiment including a hinged pawl, as wellas nested ratchets;

FIG. 10 depicts the detailed area of the embodiment of FIG. 7,illustrating a resiliently deflectable ratchet, and a break-away portionof a spacer operative to disengage the ratchet and pawl;

FIG. 11 depicts an alternative embodiment of the disclosure, including aresilient, inflatable spacer in an expanded configuration;

FIG. 12 depicts the spacer of FIG. 11, in a partially deflatedcondition;

FIG. 13 depicts the spacer of FIG. 11, in a further deflated condition,the spacer being withdrawn from the body;

FIG. 14 depicts an artificial, modular endplate to be engaged with bodytissue;

FIG. 15 depicts the end plate of FIG. 14, together with an alternativeembodiment of a spacer body including a threaded expanding portion;

FIGS. 16 and 17 depict an alternative embodiment of a spacer inaccordance with the disclosure, including a body that is expandable in anon-linear manner, or that may be combined with a ramped spacer, toaccommodate lordotic bone configurations;

FIG. 18 depicts the spacers of FIGS. 16 and 17 implanted between twobones;

FIG. 19 depicts a separable spacer portion combinable with an expandingelement of the disclosure; and

FIG. 20 depicts a resilient expanding chamber in accordance with thedisclosure, including integral projections, in a deflated configuration,and inflated between two bones of the body.

DETAILED DESCRIPTION OF THE INVENTION

Detailed embodiments are disclosed herein; however, it is to beunderstood that the disclosed embodiments are merely examples and thatthe systems and methods described below can be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present subject matter in virtually anyappropriately detailed structure and function. Further, the terms andphrases used herein are not intended to be limiting, but rather, toprovide an understandable description of the concepts.

The terms “a” or “an”, as used herein, are defined as one or more thanone. The term plurality, as used herein, is defined as two or more thantwo. The term another, as used herein, is defined as at least a secondor more. The terms “including” and “having,” as used herein, are definedas comprising (i.e., open language). The term “coupled,” as used herein,is defined as “connected,” although not necessarily directly, and notnecessarily mechanically.

In accordance with the disclosure, spinal disc spacers 100 are providedto stabilize and/or distract spinal joints, and are advantageouslyconfigured to be disposed between vertebral body end plates 202 ofsuccessive vertebrae 200. In an embodiment, spacers 100 conform to anexterior or interior configuration of the vertebral end plates 202. Assuch, a spacer 100 distributes body weight more effectively over agreater area of end plate 202, and thus prevents, reduces an incidenceof, or lessens the severity of an end plate 202 failure in patients withweakened vertebral bodies. In an embodiment of the disclosure, portionsof spacer 100 are formed with one or more rigid materials, such as metalor PEEK, and end plate contacting portions are advantageously formedwith one or more relatively more flexible, conformable materials.

With reference to FIG. 1, an expandable spacer 100 includes first andsecond engagement surfaces 102, 104, each sized and dimensioned toengage a vertebral end plate 202 (FIG. 3). In accordance with anembodiment of the disclosure, one or both of surfaces 102 areadvantageously provided with barbs, protrusions, or projections 106shaped to securely engage body tissue at a surface of vertebral endplate 202. An expandable space, reservoir, chamber, or element 108 ispositioned between surfaces 102, 104, and is operative to expand,pushing or telescoping surfaces 102, 104 apart, relative to each other.Expandable element 108 is advantageously expanded by absorbing fluid orother filling medium 118, or by being filled with a gas or liquid, inthe manner of a balloon, thereby forming a greater internally containedvolume, and a taller profile along a superior-anterior axis, or an axisdefined to extend from one bone to another, when implanted betweenvertebrae.

In an embodiment, a connector 110 is advantageously provided upon asurface of expandable element 108, or at an end of an extending fillerport 112, as shown in FIG. 1, and is operative to facilitate forming aconnection to a filling channel 114 extendable outside a patient's body.The filling medium 118 is passed under pressure through filling channel114 and port 112, to pass into expandable element 108. In anotherembodiment, connector 110 is configured as a one-way or adjustablevalve, whereby after removal of filling channel 114 and associatedfilling apparatus (not shown), a filling medium 118 cannot escape fromexpandable element 108. In another embodiment, the filling medium 118 isa substance that solidifies after being passed into expandable element108, and a valve at connector 110 is not needed.

The filling medium 118 may include a gas, for example oxygen, nitrogen,carbon dioxide, or other gas. The filling medium 118 may additionally oralternatively include a liquid, for example water, saline, oil, gel, ora pH buffered solution. Materials which harden after passing intoexpandable element 108 may include two part components, materials whichharden when exposed to air or a gas, or materials which set over time,including PMMA (polymethyl methacrylate), one or two part urethanes,epoxies, foams, resins, hydrogels, or silicones. It is advantageous ifthe filling medium 118 is biocompatible, non-toxic, or otherwise notharmful to the body in the event it is accidentally or deliberatelyreleased from expandable element 108.

In FIG. 2, filling medium 118 has been passed into expandable element108, and has caused surfaces 102, 104 to become convex with respect toan exterior of spacer 100. As may be seen in FIGS. 3 and 4, end plates202 are concave, at least in part, with respect to an exterior ofvertebral body 200. In another embodiment, surfaces 102, 104 are formedas convex or partially convex, without being under pressure from fillingmedium 118.

In the embodiment of FIGS. 1-4, a first mating section 120 includes afirst guide surface 122, and a second mating section 140 includes asecond guide surface 142. As spacer 100 is expanded by the introductionof filling medium 118, first and second mating sections 120, 140 moveapart relative to each other along respective inferior/superior axes,and first and second guide surface 122, 142 may mutual engage to preventsubstantial displacement of first and second mating sections 120, 140 ina direction transverse to the respective inferior/superior axes. In anembodiment, first mating section 120 and first guide surface 122 form,for example, a piston shaped object, and second mating section 140 andsecond guide surface 142 form a mating cylinder shaped object. As such,the piston shaped object is guided by first guide surface 122 as ittelescopes within the cylinder shaped object as defined by second guidesurface 142.

Other mutually sliding forms besides a piston and cylinder may beformed; for example first and second guide surfaces 122, 142 may havethe form of separated mutually sliding walls. First and second guidesurfaces may be rigid or resilient, thereby enabling either elevationonly along a substantially superior-anterior axis, or additionallyenabling a predetermined amount of flexion, abduction, and or rotationof bones of the joint.

First and second guide surfaces 122, 142 may form a seal to maintainfilling medium 118 within spacer 100. Alternatively, as shown in FIGS.3-4, a flexible reservoir 128 is disposed within an interior of spacer100 in fluid communication with filler port 112, the flexible reservoirexpanding to increase a height of spacer 100, and further forms a sealedspace which is operative to contain filling medium 118, maintaining theseal within a desired range of pressures.

First and second engagement surfaces 102, 104 are advantageouslyresilient, in one embodiment, so that as pressure is applied to surfaces102, 104 by passage of filling medium 118 into expandable element 108,surfaces 102, 104 may conform to the contour and surface shape of facingbones of the joint. In this manner, a support pressure by spacer 100against the bones is evenly distributed, and high pressure points orareas upon the bones are avoided.

As may be seen in FIGS. 5-6, in an alternative embodiment, first andsecond mating sections are tethered together, for example by a cord orcable 124, and relative movement is inhibited at least to the extremelimit of motion defined by a length of cable 124, and the location ofattachments of cable 124 to first and second mating sections 120, 140.In FIG. 5, at low pressure or in the absence of introduced fillingmedium 118, cable 124 and flexible sidewalls 126 are folded to enable afirst, close spacing of engagement surfaces 102, 104. In FIG. 6, afterfilling medium has been introduced as described elsewhere herein,surfaces 102, 104 are pushed apart, a distance between surfaces 102 and104 limited by a length of cable 124, and or an extended length offlexible sidewalls 126. In FIG. 6, it may be seen that surfaces 102, 104are laterally displaced with respect to each other, and a longitudinalinferior/superior axis.

Referring now to FIGS. 7-8, spacer 100 is formed as described withrespect to the embodiment of FIGS. 1-4, with distinctions as follows. Inone embodiment, a central opening, aperture, bore or through-hole 130 isformed through the body of the spacer 100. In some embodiments, thethrough-hole 130 extends from an upper surface to a lower surface of thespacer 100. A therapeutic substance (not shown) may be inserted intothrough-hole 130 prior to implanting or expanding spacer 100, wherebythe therapeutic substance is maintained in contact with end plate 202 ofvertebral body 200. Therapeutic substance may include any substancewhich confers a beneficial result to the patient, including for example,bone morphogenic material; autograft, isograft, allograft, or xenograftmaterial, artificial or natural scaffolding, lyophilized bone,freeze-dried bone allograft (FDBA), deminieralized freeze-dried boneallograft (DFDBA), hydroxylapatite, tricalcium phosphate, bioglass,calcium sulphate, antibiotics, hormones, or therapeutic drugs. In anembodiment, through-hole 130 passes completely through spacer 100,whereby a material placed within through-hole 130 may contact bothendplates 202 of adjacent vertebrae 200. As such, bone growth betweenend plates 202 is enabled, whereby a natural fixation may be achieved,for example through osteoconduction, osteoinduction, osteopromotion, orosteogenesis. In this case, it is advantageous to form a scaffold ofbone tissue, or a material which promotes bone ingrowth, such as aporous matrix.

In some embodiments, through-hole 130 is advantageously sealed withrespect to an interior of spacer 100, for example using an additionalflexible sidewall 126 forming through-hole 130, whereby filling medium118 may be contained under pressure within a sealed interior space 132residing between through-hole 130 and expanding sidewall 134.

FIG. 8 is an enlarged view of the detail area encircled in FIG. 7,illustrating an alternative embodiment for maintaining an increasedspacer 100 height in accordance with the disclosure. Expanding sidewall134 is formed with spaced ratchets 136 engageable with pawl 138 formedas one or more separate pawl sections, or may be formed as a continuousledge extending along an inner perimeter of second mating section 140.In either embodiment, pawl 138 may be formed with a resilient material,and ratchets 136 may additionally or alternatively be resilient and maycompress or deflect, whereby a ratchet may pass over a pawl, althoughthe parts are in interference. Alternatively, ratchets 136 or pawl 138may be hinged. In an embodiment, pawl 138 may be formed as a continuousextension of the material of second mating section 140, for example as amolded formation. In use, as first and second engagement surfaces 102,104 are separated relative to each other, as described elsewhere herein,successive ratchets 136 engage pawl 138, thereby substantiallypreventing first and second engagement surfaces from returning to aposition closer together to each other, whether or not pressure ismaintained within expandable element 108. The number of ratchets 136 isselected to correspond to the granularity or precision with which asurgical practitioner may wish to adjust a height of spacer 100. Forexample, each ratchet 136 may be spaced 0.5 mm to 2.0 mm from the next,but the spacing may be substantially less than or greater than thisrange, for example 0.01 mm to 10 mm. In addition, a spacing betweenratchets 136 need not be uniform, and may for example, be initiallylarger and progressively smaller. Further, ratchets 136 may bepositioned upon an inner or outer surface of either first or secondmating section 120, 140, with one or more pawls 138 being positioned ona corresponding surface of the other of first or second mating section120, 140.

Herein, the terms ratchet and pawl are used interchangeably, as eitheror both of pawl 138 and ratchet 136 may be configured to move to bepassable past the other, for example by hinging, resiliently deflecting,or resiliently compressing.

In FIG. 9, it may be seen that pawl 138 is provided with a hinge 138Aabout which pawl may rotate. A resilient member, such as a spring (notshown) may be positioned between pawl 138 and a portion of second matingsection 140, to bias pawl 138 into engagement with ratchet 136.Alternatively or additionally, discrete sections of ratchet 136 may behinged in a similar manner. FIG. 9 depicts a further embodiment, whereinratchets 136 are nested one within the other, and expand and un-nestunder pressure from said fillable material, to thereby expand a heightof spacer 100.

In FIG. 10, ratchet 136 is illustrated to resiliently extend fromexpanding sidewall 134, whereby ratchet 136 may deflect to pass pawl138, and resiliently return to a former position to engage pawl 138 oncepast. Pawl 136 may be formed in a similar manner.

FIG. 10 additionally depicts that pawl 138 may be removed from secondmating section 140 by separating a portion of second mating section 140containing pawl 138 at one or more scored or otherwise weakened partinglines 140A. In this manner, spacer 100 may be reduced in height byseparating pawl 138 from spacer 100 and moving first and second matingsections closer together. In another embodiment, first or second matingsection 120, 140, expanding sidewall 134, or other spacer 100 component,may be crushed, fractured, bent, or otherwise changed in shape orconfiguration, for example using weakened areas such as described forparting lines 140A, to facilitate removal of spacer 100.

It should be understood that throughout this specification, spacer 100may be inserted with first mating section 120 in an inferior positionwith respect to the patient's body, relative to second mating section140, or may be used in any orientation deemed therapeutically beneficialby the medical practitioner.

Referring now to FIGS. 11-13, spacer 100 is diagrammatically illustratedin an expanded configuration. For clarity, although not illustrated inFIGS. 11-13, projections 106 and other elements of spacer 100 disclosedherein may advantageously be included in this and other embodiments. Inone embodiment, spacer 100 is passed from outside the body into aninterior of the body, such boundary symbolically represented as 400 inFIG. 13. Prior to implantation, a space may be formed between vertebralbodies, using methods known in the art. In an embodiment, a cannula,trocar, or other device operative to communicate exterior and interiorportions of the body is positioned to extend into a target implantationspace for spacer 100. Alternatively, a device may be used to form anaperture in the body, through which spacer 100 may be passed. Spacer 100may then be pushed into the body, for example through a cannula, tube,device, or body opening, until it is positioned in a space betweenvertebral endplates.

In one embodiment, a portion of filler port 112 is passed into the body,and a remaining portion of spacer 100 is passed through filler port 112.For example, spacer 100 may be connected to filler port 112, deflated,and driven into a leading end 144 of filler port 112. Leading end 144may be provided with a tissue piercing edge, whereby a separate trocaror cannula need not be used in order to pass filler port 112 into thebody. Once leading end 144 is advantageously positioned within the body,filling medium 118 may be passed into filler port 112 to thereby drivespacer 100 out of filler port 112 and into the space to be expandedwithin the body, to thereafter increase in dimension as describedelsewhere herein. Following distraction, stabilization, or othertherapeutic procedure, spacer 100 may be deflated by withdrawing fillingmedium 118, after which spacer 100 may be removed in connection withfilling port 112. In an alternative embodiment, filler port 112 may beremoved after inflation of spacer 100, and removed from the body,leaving spacer 100 inflated. A valve 110 may be provided associated withspacer 100, whereby a separation of filler port 112, for example byunthreading a threaded connection, or breaking of a weakened portion,does not cause a deflation of spacer 100. In this manner spacer 100 mayremain within the body for beneficial therapeutic purpose, for anextended time period, for example days, weeks, months, or years. Inanother embodiment, spacer 100 is passed into the body through a cannulaor incision, and filler port 112 is thereafter connected for filling,and is subsequently left within the body, or is disconnected and removedfrom the body. In FIG. 12, spacer 100 is partially deflated. In FIG. 13,spacer 100 has been partly removed from the body, in this embodiment inconnection with filler port 112 at leading end 144.

Referring now to FIGS. 14-15, the spacer system can include anartificial, modular end plate. The end plate can comprise an engagementplatform 152 provided with one or more projections 106 operative topenetrate body tissue to securely maintain a position of engagementplatform 152 with respect to the body. In some embodiments, platform 152is shaped or curved to match an exterior surface of the bone with whichit is to engage. For example, platform 152 may be convexly shaped toengage a vertebral end plate 202. An aperture 154 may be providedthrough the end plate to operatively enable bone growth therethrough, orto enable the passage of body tissue or other materials. A devicecontacting surface 156 may be provided with a knurled or roughenedtexture to promote secure engagement with a body 158 of spacer 100.Alternatively, device contacting surface 156 may be provided with amechanical interlock, for example engaging digits, threaded apertures,or other interlock matable with a contacting surface 160 of spacer body158. An alternative embodiment utilizing a portion analogous to platform152 is discussed with respect to FIG. 19, below, and such descriptiontherein applies to platform 152, as well.

The modular end plate shown in FIG. 14 can work in conjunction with aspacer body. In some embodiments, the end plate can be attached to afirst vertebral body. An expandable spacer body can then be inserted inbetween the first vertebral body and an adjacent second vertebral body.Upon expansion of the spacer body, the spacer body will press againstthe end plate, thereby pushing the end plate into the first vertebralbody and provide a reinforced spacer system.

In the embodiment of FIG. 15, an alternative means of expanding spacer100 is illustrated. More particularly, a threaded shaft 162 passesthrough a nut 164 rotatably disposed in attachment to a housing 166.Shaft 162 is prevented from rotating, whereby turning nut 164 causesshaft 162 to extend or retract from housing 166, to thereby expand orcontract a height of spacer 100. Nut 164 may be rotatably connected tohousing 166, and shaft 162 prevented from rotating, by any known meansin the art. In one embodiment, an alignment projection 168 connected tohousing 166 may extend into a slot 162A within shaft 162.

Engagement platform 152 may be combined with any other spacer 100embodiment of this disclosure, enabling the selection of an engagementplatform 152 best suited to the physiology and pathology of the patient,and the goals of the medical practitioner.

With reference to FIGS. 16-18, a spacer 100 is sized and shaped to beinserted within a space formed by removal of a portion of the nucleuspulposus 204 and possibly a portion of the disc annulus 206. In theillustrated application, spacer 100 is combined with a ramped, angularspacer 170 having non-parallel opposing external faces 172, 174. In someembodiments, either one or both of the spacer 100 or the angular spacer170 are expandable. In this manner, a spacer 100 having substantiallyparallel faces may be used in locations where adjacent bony endplatesare substantially non-coplanar relative to each other, as is the casewith L5 (208) and the sacrum 210. Alternatively, either or both ofspacer 100 and an angular spacer 170 may compensate for an angulardisplacement between adjacent bony surfaces. As may be seen in FIG. 18,flexible sidewalls 126 extend to differing amounts on opposing sides ofspacer 100, while angular spacer 170 compensates for part of the angulardifferential between bony end plates 202.

Referring now to FIG. 19, spacer 100 is advantageously formed ofseparable portions 182, 184 wherein expandable element 108 is notfastened to one or both of engagement surfaces 102, 104, prior toimplantation in a patient. In this manner, access to endplate 202 isimproved. Where a fastener is passed through engagement surface 102,104, access to a device contacting face 176 is unobstructed,facilitating passage and connection of the fastener. Alternatively,where it is desired to drive projections 106 into bone or body tissue,force may be applied to non-contacting face 186 without obstruction byadditional elements of spacer 100, including for example expandableelement 108 or the other of engagement surface 102, 104. Further, suchother elements of spacer 100 may be protected during application offorce, and installed after a separable portion is implanted and fastenedto the body. In addition, once separable portions 182, 184 are securedto body tissue, they form a reliable and predictable platform orscaffold for other elements of spacer 100, and or for other implants.While four projections 106 are shown in FIG. 19, any number ofprojections 106 may be provided, depending on the type of body tissue towhich projections 106 must be connected, as well as the forces expectedto be applied to spacer 100, and the therapeutic goals of thepractitioner.

Portions 182, 184 may be analogous to platform 152, described above withrespect to FIG. 14, and such description may be applied to portions 182,184, as well. For example, device contacting faces 176 mayadvantageously engage expandable element 108, or body 158 of spacer 100,as described for device contacting surface 156.

In FIG. 20, expandable element 108 contains integrally formedprojections 106, and is a unitary structure that may be expanded withfilling medium 118 to expand and drive projections 106 into body tissue.Alternatively, projections 106 may be absent, wherein expandable element108 is maintained in place by bodily structures, or other implantedstructures. The advantage of this expandable element 108 is that theexpandable element itself serves as the entire implant. In someembodiments, to maintain the proper shape of the expandable element 108in an intervertebral space, the expandable element 108 can be formed ofcold molding. Alternatively, the wall thickness of the expandableelement 108 can be controlled to maintain a desirable shape of theimplant.

It should be understood that within this disclosure, projections 106 mayextend from material from which they project, formed, for example, bymolding. Alternatively, projections 106 may represent fasteners that arepassed through one or more portions of spacer 100, and may include forexample bone screws, barbed fasteners, staples, sutures, k-wires,polymeric anchors, or expanding anchors. Spacer 100 or any component ofspacer 100 as described herein may alternatively be connected or securedwithin the body by adhesives or cements, for example includingpolymethylmethacrylate (PMMA), methyl-methacrylate monomer (MMA), oracrylate-based plastics, although other forms of adhesives used in thebody are known in the art.

In accordance with the disclosure, spacer 100 may be used to facilitateor promote inter-body fusion (IBF), and may provide stabilization and ordistraction while reducing stress points upon bony structures, and inparticular, fragile vertebral end plates. In addition, spacer 100 may beused alone or in combination with other spacers to create or restorehealthy orientation of curvature of the spine or other jointed bones,for example to correct for extreme lordosis.

Spacers 100 may be formed to closely conform to patient physiology, forexample by being shaped based upon imaging of a patient prior tomanufacture and or implantation. Spacers 100 of the disclosure may beimplanted using any known or hereinafter developed surgical implantationtechniques, including minimally invasive, cannula based, mini-invasive,or fully open access, as well as anterior, posterior, anterio-lateral,or posterior-lateral approaches.

While a positioning of spacer 100 between adjacent vertebrae isillustrated and described herein, it should be understood that spacer100 may be inserted into an interior of a vertebral body 200, to providesupport from within the vertebrae. In this application, first and secondengagement surfaces 102, 104 may advantageously be concave, to betterconform to an interior configuration of the vertebral endplates 202. Oneor more vertebrae of a patent may be supported in this manner. Further,where spacer 100 is positioned between adjacent vertebrae, more than onespacer 100 may be used between adjacent vertebrae, and spacer 100 may bepositioned at multiple levels, between different adjacent vertebrae.

Moreover, in addition or in alternative to the spine, spacer 100 may bepositioned within other joint spaces of the body, for example in jointsof the fingers, hand, wrist, elbow, shoulder, hip, knee, ankle, foot,and toes, to effectuate therapeutic distraction or stabilization of suchjoints. Spacer 100 is thus sized and shaped to correspond to the jointin which spacer 100 will be implanted, whether temporarily, or for aprolonged post-surgical period.

Any or all of spacer 100 may be formed using biodegradable materialswhose use is understood within the art, whereby after stabilization hasbeen achieved, spacer 100 may dissolve or otherwise deconstitute,advantageously without leaving potentially harmful material within thebody. This may be advantageous, for example, where bone formation hasfused adjacent vertebrae, and spacer 100 is no longer needed in order tofoster stabilization. Alternatively, spacer 100 may be used incombination with other stabilization or therapeutic devices, and mayonly be needed for an initial period, during which, for example, healingof the body, curing of an additional device, or bio-integration ofanother device takes place, after which spacer 100 may advantageouslybiodegrade.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed herein above. In addition, unless mention was made above tothe contrary, it should be noted that all of the accompanying drawingsare not to scale. A variety of modifications and variations are possiblein light of the above teachings without departing from the scope andspirit of the invention.

All references cited herein are expressly incorporated by reference intheir entirety. In addition, unless mention was made above to thecontrary, it should be noted that all of the accompanying drawings arenot to scale. There are many different features to the present inventionand it is contemplated that these features may be used together orseparately. Thus, the invention should not be limited to any particularcombination of features or to a particular application of the invention.Further, it should be understood that variations and modificationswithin the spirit and scope of the invention might occur to thoseskilled in the art to which the invention pertains. Accordingly, allexpedient modifications readily attainable by one versed in the art fromthe disclosure set forth herein that are within the scope and spirit ofthe present invention are to be included as further embodiments of thepresent invention.

What is claimed is:
 1. A spinal device comprising: a first bonecontacting section having a first surface conformable to a surface of afirst bone; a second bone contacting section having a second surfaceconformable to a surface of a second bone; an expandable elementpositionable between said first and second bone contacting sections, theexpandable element having an inlet port through which a filling mediummay be passed into said expandable element under a filling pressuresufficient to expand and increase a dimension of said expandable elementalong an axis extending between the first bone and the second bone; atleast one pawl extending from at least one of said tarst or second bonecontacting sections; and at least one ratchet extending from saidexpandable element, said at least one ratchet passable past andengageable with said at least one pawl when said expandable element isexpanded by pressure, wherein at least one of the first bone contactingsection or the second bone contacting section changes shape as fillingmedium is passed into the device, wherein the spinal device furthercomprises a throughbore that extends through the device from the firstbone contacting section to the second bone contacting section, whereinthe throughbore is formed by a flexible sidewall.
 2. The device of claim1, wherein at least one of said at least one pawl and at least one ofsaid at least one ratchet are resiliently deflectable to be passablepast the other.
 3. The device of claim 1, wherein at least one of saidat least one pawl and at least one of said at least one ratchet arehinged to be passable past the other.
 4. The device of claim 1, whereinsaid inlet port includes a valve operative to maintain a pressure ofsaid filling medium within said expandable element.
 5. The device ofclaim 1, wherein said tilling medium increases in solidity after beingpassed into said expandable element.
 6. The device of claim 5, wherein asubstantial portion of said device biodegrades after said filling mediumincreases in solidity.
 7. The device of claim 1, wherein said first andsecond bone contacting sections and said expandable element includemutually communicating apertures whereby a channel is formedtherethrough.
 8. The device of claim 7, wherein a material for promotingbone growth between said first and second bones is placed inside saidchannel.
 9. The device of claim 1, wherein the first bone contactingsection includes a first side wall extending towards the second bonecontacting section, and the second bone contacting section includes asecond side wall extending towards the first bone contacting section,the first and second side walls telescoping in mutual relativeconformity.
 10. The device of claim 1, further including an extensionextending from said inlet port to a position away from bones of thejoint.
 11. The device of claim 10, wherein said extension is separablefrom said inlet port.
 12. The device of claim 1, further includingprojections extending from at least one of said first and second bonecontacting sections to engage bone of the joint, thereby securing saidat least one of said first and second bone contacting sections fromlateral movement relative to an axis extending from said first bone tosaid second bone.
 13. The device of claim 1, wherein at least one ofsaid first or second bone contacting sections is separable from saidexpandable element.
 14. The device of claim 1, wherein said bones arevertebral bodies.
 15. The device of claim 1, wherein said expandableelement is formed of a resilient material.
 16. The device of claim 1,wherein at least one of said first and second bone contacting sectionsresiliently conforms to a shape of the first or second bone,respectively.
 17. The device of claim 1, where said expandable elementexpands non-uniformly, thereby disposing said first and second bonecontacting sections in substantially non-parallel conformity withrespect to each other, when said first and second bone contactingsections are in contact with the first and second bones, respectively.18. A spinal device, comprising: a first bone contacting section havinga first resilient surface conforming to a surface of a first vertebralendplate of a first vertebra; a second bone contacting section having asecond resilient surface conforming to a surface of a second vertebralendplate of a second vertebra; an expandable element positioned betweensaid first and second bone contacting sections, the expandable elementhaving an inlet port through which a filling medium may be passed intosaid expandable element under a first pressure to expand and increase aheight of said expandable element along an axis extending between thefirst bone and the second bone; at least one pawl extending from atleast one of said first or second bone contacting sections; and at leastone ratchet extending from said expandable element, said at least oneratchet passable past and engageable with said at least one pawl whensaid expandable element is expanded by pressure, and not passable pastsaid at least one pawl when said at least one ratchet and at least onepawl are engaged and said filling medium is under a second, lowerpressure, whereby a height of said device is substantially maintained,wherein at least one of the first bone contacting section or the secondbone contacting section changes shape as filling medium is passed intothe device, wherein the spinal device further comprises a throughborethat extends through the device from the first bone contacting sectionto the second bone contacting section, wherein the throughbore is formedby a flexible sidewall.
 19. The device of claim 18, wherein said atleast one pawl and said at least one ratchet are disengageable, wherebya height of said device may be reduced.